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Ventilation Modes and Current Trends

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Title: Ventilation Modes and Current Trends


1
Ventilation Modes and Current Trends
  • Denny Gish, BSRT, RRT
  • Clinical Specialist, Adult Respiratory Care
  • Legacy Emanuel Hospital and Health Center

2
Objectives
  • Review current ventilator modes
  • Mode descriptions
  • Review trends in Respiratory Care
  • ARDS Network recommendations
  • Best PEEP
  • Recruitment Maneuvers
  • Identify various methods of High Frequency
    Ventilation

3
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4
Modes of Ventilation
  • The Critical Question...
  • How do you choose ?

5
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6
What Starts the Breath ?
  • Controlled or timed breaths
  • Controller is really an interval timer
  • Assisted breaths are triggered by patient
    inspiratory effort in addition to Controlled
    breaths
  • Spontaneous breaths allowed in some modes

7
What Ends the Breath ?
  • Preset pressure reached
  • Preset volume is delivered
  • Preset time has elapsed

8
Ventilator Settings
  • Mode Volume control, Pressure control,
    Spontaneous, etc (how the breath goes in)
  • VtTidal Volume (size of breath 8-10 cc/kg,
    4-6cc/kg for ARDS)
  • Volutrauma can be as damaging as Barotrauma
  • f Frequency (rate breaths per minute 10-15
    bpm)
  • PEEP Positive End Expiratory Pressure (gt/ 5
    cmH20)
  • IP Inspiratory Pressure (ideally lt 30 cmH20)
  • FIO2 Fraction of Inspired Oxygen
  • All ordered by MD or by unit protocol
  • Ti or V Inspiratory time or Flowrate (how long
    it takes the breath to go in - generally per RT
    discretion based on pt comfort condition)

9
Ventilator Measurements
  • Vt tidal volume - ccs or mls
  • f frequency, breaths per minute - bpm
  • Ve minute ventilation ( Vt f) liters per
    minute
  • IE Ratio insp time to exp time (norm is 12)
  • PIP (or PAP) Peak Inspiratory Pressure cmH20
  • MAP Mean Airway Pressure cmH20
  • PEEP Positive End Expiratory Pressure cmH20
  • Pplat Plateau or Static Pressure (true lung
    inflation pressure (eliminates airway tubing
    resistance) cmH20
  • Cstatic Static Compliance (normal 40-60
    ml/cmH2O)
  • Learn to read measurements off vent screen

10
Some Basic Modes
  • Volume Control set Vt f, pt may assist
  • Pressure Control set IP f, pt may assist
  • Synchronized Intermittent Mandatory Ventilation
    set Vt f, pt may take unassisted spontaneous
    breaths as well
  • Mandatory Minute Volume Ventilation MMV
    mandatory breaths are only provided if
    spontaneous breathing is not sufficient and below
    the prescribed minimum ventilation.
  • Pressure Support pts own Vt f, supported by
    insp boost to augment pts insp efforts. Pt may
    breathe deep or shallow, fast or slow w/o
    intervention from vent.

11
Name that Mode of Ventilation
  • Evita XL Ventilation Modes
  • CMV Continuous Mandatory Ventilation
  • AKA- Assist/Control
  • MMV Mandatory Minute Ventilation
  • AKA-Smart SIMV
  • PCVPressure Controlled Ventilation
  • used when PIP is gt35
  • APRV Airway Pressure Release Ventilation
  • Low compliance disorders
  • CPAP-Continuous Positive Airway Pressure with
    or without PS

12
Draeger V 500

  • Ventilation mode
  • VC-CMV - Draeger XL has CMV, but it is NOT the
    same!
  • VC-ACWorks like CMV on the Draeger XL
  • VC-MMV-Draeger XL has MMV and it performs exactly
    like the VC-MMV on the V500
  • PC-AC Draeger XL has PCV
  • PC-APRV with AutoRelease - Draeger XL does not
    have an autorelease function
  • SPN-CPAP/PS/VS-Draeger XL has CPAP mode that has
    Pressure Support capabilities, but no Volume
    Support







13
NowPuritan Bennet 840
14
Viasys Avea
15
Servo I buy
16
More Advanced Modes
  • Volume Support pts own f w/PS for goal Vt.
    Vent guarantees Vt by adjusting the PS based on
    lung compliance and/or resistance to ensure a
    preset tidal volume.
  • Pressure Regulated Volume Support set f and goal
    Vt, pt may assist. Ventilator automatically
    adjusts pressure up or down, from breath to
    breath, as patient's airway resistance and lung
    compliance changes, in order to deliver the goal
    tidal volume.
  • Volume Control Plus same as PRVC
  • Airway Pressure Release Ventilation High and low
    pressures set w/minimal timed releases to
    facilitate gas exchange, high MAP w/very Inverse
    IE ratio. Pt may breathe spontaneously during
    high pressure holds.

17
ARDS Current Definition
The 1994 North American-European Consensus
Conference (NAECC) Criteria
  • Onset - Acute and persistent
  • Radiographic - Bilateral pulmonary infiltrates
  • Oxygenation - regardless of the PEEP, with a
    Pao2/Fio2 ratio ? 300 for ALI and ? 200 for ARDS
  • Exclusion criteria - Clinical evidence of Left
    Atrial Hypertension or a PAOP of ? 18 mm Hg.

Bernard GR et al., Am J Respir Crit Care Med 1994
18
Tidal Volume Strategies in ARDS
  • Traditional Approach
  • High priority to traditional goals of acid-base
    balance and patient comfort
  • Lower priority to lung protection
  • Low Stretch Approach
  • High priority to lung
  • protection
  • Lower priority to traditional goals of acid-base
    balance
  • and comfort

19
Physiologic Benefits vs Patient-Important
Outcomes
  • PaO2 improvement vs Survival Benefit
  • For ARDS, inhaled nitric oxide improves PaO2, but
    not mortality
  • (Taylor et al, JAMA 20042911603)
  • High tidal volumes in patients with ARDS improves
  • PaO2, but mortality is lower for small tidal
    volumes
  • (ARDSnet, N Engl J Med 2000 3421301)
  • For ARDS, prone position improves PaO2, but not
  • mortality
  • (Gattinoni, N Engl J Med 2001345568)

20
ARDS Network Low VT Trial
  • Patients with ALI/ARDS of lt 36 hours
  • Ventilator procedures
  • Volume-assist-control mode
  • 6 vs. 12 ml/kg of predicted body weight Vt
  • (PBW/Measured body weight 0.83)
  • Plateau pressure ? 30 vs. ? 50 cmH2O
  • Ventilator rate 6-35 to achieve a pH goal
  • of 7.3 to 7.45
  • Oxygenation goal PaO2 55 - 80 mmHg,
  • SpO2 88 - 95
  • )

ARDS Network. N Engl J Med. 2000.
21
Lung Recruitment
  • First and foremost performed to provide an
    arterial oxygen saturation of 90 or greater at
    an FiO2 of less than 60
  • Recruitment of nonaerated lung units (open-lung
    concept) but risk of regional lung overinflation
  • a highly controversial issue!

22
Recruitment Maneuvers (RMs)
  • Effective in improving arterial oxygenation at
    low PEEP and small tidal volumes.
  • Recruitment maneuvers may be poorly effective or
    deleterious, inducing overinflation of the most
    compliant regions, hemodynamic instability, and
    an increase in pulmonary shunt resulting from the
    redistribution of pulmonary blood flow toward
    nonaerated lung regions.
  • The effect of recruitment may not be sustained
    unless adequate PEEP is applied to prevent
    derecruitment.
  • Many questions still need to be answered

23
PEEP in ARDSHow much is enough ?
  • PEEP, by avoiding repetitive opening and collapse
    of atelectatic lung units, could be protective
    against VILI
  • PEEP, has been shown to prevent surfactant loss
    in the airways and avoid surface film collapse.
  • The lung is kept open by using PEEP to avoid
    end-expiratory collapse.
  • High PEEP should make the mechanical ventilation
    less dangerous than low PEEP.

Levy MM. N Engl J Med. 2004. Rouby JJ, et al. Am
J Respir Crit Care Med. 2002. Gattinoni L, et al.
Curr Opin Crit Care. 2005.
24
Optimizing PEEP
  • Optimizing PEEP.
  • PEEP level is at low lung volume and below
    critical opening pressure.
  • PEEP increased to optimize compliance.

25
larson
26
ARDS Network Low VT Trial
  • Allowable combination of FiO2 and PEEP

FiO2 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7 0.7
0.8 0.9 0.9 0.9 1.0 1.0 1.0 1.0
PEEP 5 5 8 8 10 10 10
12 14 14 14 16 18 18 20 22 24
27
APRV Mode
  • First described 1987
  • Baseline airway pressure is the upper CPAP level,
    and the pressure is intermittently released to
    a lower level, thus eliminating waste gas
  • Time spent at low pressure (short expiratory
    time) prevents complete exhalation maintains
    alveolar distension

28
APRV Evidence
  • Prospective, randomized intervention study
    (N45) PC/PS vs. APRV patients with ALI
  • Oxygenation was significantly better in APRV
    group
  • Sedation use and hemodynamics were similar

Puntsen, Am J Respir Crit Care Med,2001
29
APRV settings
30
If this...
why not this?
- John B. Downs, MD
31
High Frequency VentilationHFOVOscillatory
HFJVJETHFPVPercussive
32
High Frequency Percussive VentilationHFPV
  • -High Frequency Percussive Ventilation (HFPV) is
    a hybrid form of high frequency ventilation.
  • -This concept of pneumatic diffusive / convective
    protocols is not related to high frequency
    vibration, jet insufflation or electronically
    controlled crank or magnetically servoed dynamic
    oscillators.

33
Rationale for HFV-Based Lung Protective Strategies
  • HFV uses very small tidal volumes
  • Avoids excessive end-inspiratory lung volumes
  • Allows for higher end-expiratory lung volumes to
    achieve better recruitment
  • HFV uses much higher respiratory rates
  • Allows for maintenance of normal PaCO2 even with
    very small tidal volumes

34
High-frequency Ventilation
  • HFOV may improve oxygenation when used as a
    rescue modality in adult patients with severe
    ARDS failing CV.
  • HFOV may be considered for patients with severe
    ARDS
  • FiO2 gt 0.60 and/or SpO2 lt 88 on CV with PEEP gt
    15 cm H2O, or
  • Plateau pressures (Pplat) gt 30 cmH2O, or
  • Mean airway pressure ? 24 cm H2O, or
  • Airway pressure release ventilation Phigh ? 35 cm
    H2O
  • HFOV for adults with ARDS is still in its infancy
    and requires further evaluations.

Higgins J et al., Crit Care Med 2005
35
High Frequency Percussive VentilationHFPV
  • -High Frequency Percussive Ventilation (HFPV) is
    a hybrid form of high frequency ventilation.
  • It is a combination of convective style
    ventilation and percussive high frequency linked
    together.

36
Inverse Ratio Ventilation
  • Technique used prior to latest generation of
    vents
  • Used in refractory hypoxemia
  • Another way to increase FRC
  • Expiratory time is longer than inspiratory time.
  • Heavy sedation/paralytics required
  • Fluids, pressors usually needed as well due to
    decrease in venous return to thorax
  • Sometimes occurs inadvertently by erroneous vent
    changes or pt agitation high RR. Must be
    corrected!

37
Other Advanced Interventions
  • Require separate or additional machines
  • Inhaled Nitric Oxide selective pulmonary artery
    vasodilator. Used for pulm htn, lg saddle PEs,
    to reduce intrapulmonary shunting improve V/Q
    matching. Prohibitively expensive, may cause
    methemoglobin buildup
  • High Frequency Ventilation high frequency (gt200
    breathes per min)
  • HFOV, HFJV, HFPV
  • Extracorporeal Membrane Oxygenation (ECMO)
    similar to bypass pump used in cardiac surgery

38
Adjuncts
  • Recruitment Maneuver
  • PEEP - does not recruit alveoli, but can help
    maintain alveolar stability
  • Prone positioning has not changed morbidity or
    mortality outcomes in ARDS, but has been shown to
    help improve oxygenation

39
A man suffered from insomnia and dyslexia. He
was also an agnostic. What did he do?
  • He stayed up all night wondering if there was a
    DOG.
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